Reaction of hydrocarbons



M. M. HOLM ETAL REACTION op HYDRocARBoNs Filed June 26, 1939 INVENTORS vide a new and improved process for the alkyla- 1 rated high antiknock motor fuel hydrocarbons, y

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high antiknock Value, bromine number, gravity vby contact with sulfuric acid as the alkylation Patented Dec. 3, 1940 REACTION OF HYDROCARBONS Melvin M. Holm, San Francisco, Eugene H. .Oak-

ley, Berkeley, and Robert L. Humphreys, El Segundo, Calif., assignors to Standard Oil Company of California, San Francisco, Calif., a corporation of Delaware Application June 26, 1939, Serial No. 281,168

8 Claims. (Cl. 196-10) This invention relates to an improved process for the manufacture of high antiknock motor' fuel hydrocarbons by the reaction of paraiinic hydrocarbons with olefinic hydrocarbons.

It is known that isoparanic hydrocarbons can be reacted with olei'lnic hydrocarbons to make isoparaiiinic hydrocarbons having a number of carbon atoms equal the sum of the carbon atoms of the initial isoparailin and olen. For example, the alkylation of isobutane with a butene to make isooctane by contact and vigorous agitation with sulfuric acid is disclosed by British Patent No. 479,827. The product of such alkylation reactions will be referred to herein as an alkymer.

In the manufacture of motor fuel by means of the alkylation of isoparaffins with olens, especially in the manufacture of aviation gasoline, it is necessary that the p roduct meet certain quality standards, such as those relating to uct is obtained.

In eifectingthe alkylation of isoparaiiins with olens the alkylation catalyst, such as sulfuric acid, is continuously mixed withA the olefin or olens and the isoparafhn or isoparafiins' to be alkylation reaction and then passed to a separating zone where the catalyst; such as sulfuric acid, separates from the hydrocarbons.

According to this invention the concentration of `alkyl acid sulfate, resulting from the reaction of sulfuric acid and olen, is maintained below certain critical values, which are related to the quality of the product, and especially the 'antiknock value, bromine number and yield of aviation gasoline cut in the product. This concentration of alkyl acid sulfate in the sulfuric acid catalyst is maintained at a maximum of about two per cent by weight of the sulfuric acid when operating at a temperature below about 40 F. However, even at temperatures below about 40 F., for a maximum use of the sulfuric acid as an alkylation catalyst, it is preferable that the concentration of alkyl acid sulfate -be not more than about one per cent by weight of the acid. For operation at temperatures above about 40 F.' the alkyl acid sulfate concentration should in no case be above about one percent by weight of the acid, and preferably at a value below about one per cent to minimize side reactions.

This invention may be better understood by and boilingrange, but due to numerous difllculties encountered in the operation of an alkylation` process for the production of good quality motor fuel, it has heretofore been impossible to obtain a product having as high a quality as is desired.

It is one object of the present invention to manufacture isoparailinic motor fuel hydrocarbons having a high antiknock value.

It is another object of this invention to provide a new and improved process for the alkylation of isoparafd'ns witholens to produce saturated high antiknock motor fuel hydrocarbons.

Still another object ofthis inventionis to provone specific embodiment exemplifying the invention is shown in the figure. In this embodiment a Amixture of normally gaseoushydrocarvbons containing an isoparaiiln to be yalkylated andthe olens may be introduced through line I, while the catalyst, sulfuric acid, is introduced through line 2. 'I'he mixture of catalyst, olens and isoparaffin are rapidly passed through line 3 to a mixing oragitating device such as a mixing tion of isoparafns with olefins to produce satuthe productof which process contains a high proportion of such hydrocarbons boiling in the aviation gasoline boiling range.

Another object of this invention is to provide a new and improved process for the alkylation of -isoparailns with olens to produce an alkymer product having a better bromine number anda better gravity. Y

Other and further important objectsV of this invention will become apparent from the following description and appended claims,

Briefly, the process of this invention comprises the alkylation of isoparains with olefins the hydrocarbons, including theolens and isoparafn, are thoroughly mixed to assist the alkylation reaction, and then the resulting mixture discharged through line 5 into a separator 6 in which the sulfuric `acid catalyst separates from the hydrocarbons by gravity.A

Fromseparator E hydrocarbons, and any un- 'separated sulfuric acid, are Withdrawn through line 1 controlled by valve 20 and may be passed into a neutralizer 8, in which the hydrocarbons are contacted with a neutralizing agent, such as a caustic alkaline material, or the like, introcatalyst in which the alkyl-acid sulfate concen-` tration, which results from the reaction between olefin and sulfuric acid, is maintained below cerreferonce to the accompanying drawing wherev pump 4. In this mixing pump the catalyst and tain critical values so that a good quality prodv alkylated. This mixture is agitated to assist the duced to 8 through line 9. to remove any acid present in the hydrocarbons. Used caustic which has settled in 8 may be Withdrawn through line. l0, or may be recirculated by pump II through lines I2 and 9. From the neutralizar 8, the hydrocarbons may be passed through line 41`to a settling tower I3, where alkali settles out from the hydrocarbons and is withdrawn through line I4 or may be recirculated to the neutralizer 8 by pump I5 through lines I6 and 9. Fresh caustic may be added through line I1,

' communicating with lines I6 and 9, as needed.

i Some of the hydrocarbons withdrawn from the separator 6 through line 1 may be passed into line I8 controlled by valve I9 and thence recirculated through `the mixer` 4 and separator- 6. 'Ihese hydrocarbons will include some of the alkymer product produced and -a substantial quantity of unreacted isoparaiiin.

Y Spent acid may be removed from the system from the lower part of separator 6 through line 2 I controlled by valve 22, or recirculated through line 2 controlled by valve 23. Fresh acid may beadded to Vthe system through line 24, controlled by valve 49, which communicates with line 2.

From the upper part of settler I3, hydrocarbons, which include the alkymers and unreacted normally gaseous hydrocarbons, may be removed through line 25 and passed to an alkymer stabilizer 26, having therein heating coil 21 or equivalent heating means. 1f vthe olenic or isoparafnic gases charged to the system contain normal parafiin, the mixture of normal and isoparan'in, such as normal and isobutane, may be removed from the stabilizer 26 overhead through line 28 controlled by'valve 48; condensed in condenser 29, and collected in receiver 30. Some of the condensate in receiver 30 may be returned to the upper partof stabilizer 26 as reflux through line controlled by valve 33 and charged back4 to the mixing zone through line I. Moreover, the mixture of normal and isopara'in may be passed directly to mixer 4 through lines 32 and 3, if desired. 'I'he material being returned through line 32 may be liquified, when desired, by any known means, such as a condenser or compresser, not shown.

'I'he alkymer product may be withdrawn from stabilizer 26 through line 34 controlled by valve 35 and passed into a still 36 where the alkymer product may be distilled into any desired cuts, although it will usually be desirable to take on an aviation gasoline cut overhead from this still. It is a significant feature' of this invention that when the concentration of alkyl acid sulfate in the sulfuric acid catalyst is maintained below a value of about one per cent, the alkymer product has a higher antiknock value and a lower bromine number than when this concentration becomes higher than this value, and the alkymer product taken ofi overhead from still 36 gives a higher yield of high antiknock motor fuel hydrocarbons boiling in the aviation gasoline boiling range (initial boiling point about F. and 90% off at about 275 F.)

The mixture of isoparailln and normal parailn, such as isobutane and normal butane, in receiver 30 may be passed through line 31 to an isoparaflin still 38 from which normal paraffin is removed as bottoms through line 33 and isoparaiiin is taken 01T overhead through line 40. condensed in cooler 4I and collected in receiver 42. Some isoparailin from receiver 42 may be returned to the isoparaffin still as reflux through line 43, if desired. From receiver 42 isoparamn -may be returned-to the 'mixing zone through lines'44 and 32, orwithdrawn from the system through line 45, as desired. 1

Usually the normally gaseous hydrocarbons charged to the systemwill comprise a mixture of oleins, isoparanin and normal vparaiin and such mixture may be introduced through line 46. ShouldNolenns and isoparamns be charged separately, the olens may be lintroduced through line 46 and isoparamn through line I.

In accordance with this invention the concentration of alkyl acid sulfate in the sulfuric acid in the zone in which the alkylation reaction is effected, especially in mixer 4, is maintained at least below about one per cent, preferably, for all temperatures of operation, but may be as high as about two per cent for temperatures below about 40 F. This concentration may be maintained below such critical values by introducing fresh acid through line 24, by controlling the feed rate of the charge passing through line 3 to be alkylated, which effects a control -of the ratio of olefin to sulfuric acid, by controlling the degree of contacting or mixing in mixer 4, or by controlling the ratio of isoparaflin to olen.. in line 3 where the olefin rst contacts the sulfuric acid and `in the mixer 4, or by controlling any number or all of these factors together to maintain the desired alkyl acid sulfate concentration in the sulfuric acid. The ratio of isoparain to olefin may be controlled by the addition of a greater quantity of isop'arafn through line 32, line 44,

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line I or line I8, or by lowering the quantity of olefin supplied either through line I or line 46. Thus, should the concentration of alkyl acid sulfate in the sulfuric acidl become too high as indicated by a direct measurement, by the degradation of the product, or by any other means, it

can be lowered by any of the foregoing methods or means.

Although the alkylation reaction may be eifected with the isoparafins and olens in the gas phase, it is preferred to operate with these hydrocarbons in the liquid phase. The sulfuric acid used may be of any concentration known to effect the alkylation reaction, but' it is preferred to use sulfuric vacid of concentration between about per cent'and about 98 percent. The temperature may be any temperature known for the alkylation reaction with sulfuric acid as the catalyst, but it is preferred to operate with a temperature of from about 15 F. to about 150 F. Although the process of this invention may be used to effect the alkylation of any isoparaiiin with any olen known to be capable of such reaction, it is especially suitable for the alkylation of normally gaseous isoparains with normally gaseous olens, such as are usually present in gases obtained from a cracking operation, for example, the alkylation of isobutane or isopentane with propylene or any of the butylenes.

Having thus disclosed our invention relating to the improved process of alkylating isoparains with olens to produce high antiknock motor fuel hydrocarbons, we claim:

l. Process of alkylating isoparaiins with olens which comprises contacting isoparafn and olefin with sulfuric acid of alkylating concentration and maintaining the concentration of alkyl acid sulfate in the acid below about one per cent by weight of the acid. l

2. Process of alkylating isoparafiins with oleiins which comprises contacting isoparafin and olefin with sulfuric acid of alkylating concentration at temperatures below about 40 F. and maintaining of alkylating concentration as a catalyst and maintaining the concentration of alkyl acid sulfate in the sulfuric Iacid below about one per cent by weight of the sulfuric acid.

4. Process of reacting isobutane with butylenev to produce isooctane therefrom which comprises alkylating isobutane with butylene by contact with sulfuric acid of alkylating concentration and maintaining the butyl acid sulfate concen` tration in the acid below about one per cent by weight of the acid.

5. Process of reacting isoparaflns with olefinsi of contacting of the isoparain with the sulfuric acid, controlling the ratio of olen tosulfuric acid, and controlling the ratio of isoparamn to olefin.

6.l Process of reacting isoparafns with oleflns 4 .to produce alkymers therefrom which comprises and agitating the isoparafn and olefin with sulfuric acid of alkylating concentration and maintaining the concentration of alkyl acid sulfate in the sulfuric acid below about one per cent to produce a good quality product by controlling the ratio of olen to sulfuric acid.

. 7; Process of reacting isoparafins having less than six carbon atoms per molecule with normally gaseous oiens to make a product high in antiknock value, low in bromine number and high in aviation gasoline content which comprisesagitating saidisoparaiins and said olefins with sulfuric acid of alkylating concentration in a reaction zone under conditions effective to alkylate isoparafiins with olefins, maintaining the concentration of alkyl acid sulfate in the sulfuric acid in said reaction zone below about one per cent by Weight of the acid to make a product high in antiknock value, low in bromine number and high in aviation gasoline content.

8. Process of reacting isoparains having less than six carbon atoms per molecule with" normally gaseous olens to make a product high in antiknock value, low in bromine` number and high in aviation gasoline content which comprises agitating said isoparains and saidy olens with. sulfuric acid of alkylating concentration in a re-` action zone at a temperature below about 40 F. under conditions effective to allmlate isoparaiins with olens, maintaining the concentration of alkyl acid sulfate in the sulfuric acid in said reaction zone below about two per cent by weight of the' acid to make a product high in antiknock value, low in bromine number and high in aviation gasoline content.

MELvrN M. HoLM; EUGENE H. OAKLEY. ROBERT Ih HEMPHREYS. 

